Process for the preparation of arsenic compounds



Patented July I 31, 1928 ARTHUR lama-or BERLIN, AND cum. RATE, or BANGSDORF, GERMANY.

. PROCESS FOR THE PREPARATION or ARSENIC COMPOUNDS.

No Drawing. Application filed July 13, '1926, S.eria1 No. 122,266, and in Germany July 22, 1925.

The object of this invention is the preparation of compounds containing two arsenic molecules, connected by a double bond, of

the general formula R As As H, wherein R and R may be similar or dissimilar, substituted or unsubstituted, aliphatic, isocyclic or heterocyclic organic radicals.

- We have discovered that this type of compound. can be prepared by treating a,mix'- ture of an arsine and an arsonic acid with -a reducing agent whereby a reduction of the arsonic acid takes place followed immediately by a condensation to form the desired compound. Another method of preparing this type of compound is described in our copendi'ng application filed on even date herewith.

In carrying out the process of this invention the arsine and the arsonic acid are first mixed in an acidic aqueous solution .in'a molecular ratio, an excess of a reducing agent, such as hypophosphite of sodium, is then added in successive small amounts to the cooled solution. On standing for a short while the condensation product RAs= AS-R precipitates.

A further advantage of our invention is the factthat the formation of the arseno compounds from the mixture takes place in erably better than when working w PP cation of heat.

' Emamples.

5. 5 grams of 2-hydroxy-5-pyridyl ar- SOIllc acid were dissolved in 100 cc. of water containing an equimolecular amount of sod um hydroxide; this solution was then ac dlfied with an excess of hydrochloric acid. An aqueous hydrochloric acid solution of 4.:hydroxy-3-amino phenyl arsine produced 1n the well known way from 7 grams 4-hydroxy-3-amino phenyl arsonic acid was then stirred in and the mixture cooled. 1 gram potassium iodide and 10 grams sodium hypophosphite were then add ed and the mixture well agitated out of contact with the air. After standing for about half an-hour 10 grams of sodium hypophosphlte were again added and the mixture allowed to stand over night. A slight precipitate or cloudiness due to the formation of the condensation product appeared shortly after adding the first portion of the reduc- 111 agent, this precipitate rapidly increased. After standing the product appeared as a flocculent precipitate which was filtered off and washed with hydrochloric acid, water and ether. Yield 94% of the theoretical.

the cold. Hereby a solubility of the re- The e i takes p a e a cording to the sulting product is obtained which is considfollowing equation:

o 58 0i: A HQAS NH, As=As NH,

H, 31110 'OH OH H0 011 (2) 2.1 grams of 2-hydroxy-5-pyridyl arsonic acid were dissolved in 50 cc. water an 10 cc. concentrated hydrochloric acid. To the cold solution is added a solution of 4- hydroxy-3-aminophenyl arsine, which has been produced by reducing 3 grams l-hydroxy-3-nitrophenylarsonic' v acid by means of zinc dust and hydrochloric acid. 0.5 gram potassium iodide and 5 grams sodium dyl arsonic acid were dissolved in 50 cc. concentrated hydrochloric acid. A solution of N hypophosphite are then added to the cold clear mixture. After stirring for half an hour another 5 grams sodium hypophosphite are added. The mixture is then allowed to stand out of contact with air for 12 hours.

About 94% yield were obtained. Thereaction takes place according to the following equation:

4-hydroxy-3-amino phenyl arsine which is produced by reducing 4-hydroxy-3-nitrophenyl arsonic acid by means of zinc dust and hydrochloric acid-is added to the cold solution. 0.5 gram otassium-iodide and grams-sodium hy p osphite 'a-re then' added (4') '2.1"gra'ms 2-hydroxy-pyridyl-5 -arsonic acid were dissolved in 10 cc.-concentra-ted hydrochloric acid. .To the solution-isadded a solution of 4-aminophenyl-arsine' obtained;

' by reducing 2.2 grams'arsonilicfacid with zinc dust and hydrochloric-acid- On mixing the solutions a precipitate is formed immedle ately. 0.5 gram potassium iodide -,.and a 5 E0 HN:

N V (5) 1.8 grams 3-amino-4-hydroxy-phenyl arsomc acid are dissolved in 50 cc. concentrated hydrochloric acid. To the cold solution is added a solution of 4-hydroxy-3- amino phen l arsine obtained by reducing 3 grams 4-hyd roxy-3-nitrophenyl arsonic acid with zinc dust and hydrochloric acid. 0.5 gram potassium iodide and 5 grams sodium hypophosphite are, added to the cold clear solution. After agitating for hour 5 grams sodium hypophosphite are agaln I mN AE-{OH Hm on no What we claim is: "1 v 1. Process for the preparation of arsenic compounds containing the group As =As which comprises reducing an organic 'arsonic acid in the presence of an organic arsine containing the group AsH by means ofa reducing agent.

2. Process for the preparation of arsenicv compounds containing the group -As=As which comprises reducing an organic arsonic acid in the presence of an organic arsine containing the group -.AsH in acid solution by means of a reducing agent. 1 v

3.'Process for the "preparation of arsenic compounds containing the group As=As which comprises mixing an acidic aqueous out of contact with air.

ing the temperature-and adding more reduc-- mg agent'no further deposit was formed. The reaction takes place according to the following equation grams sodium hypophosphite are added.-

The precipitate The mixture is agitated for hour; subsequently 5 grams sodium hypophosphite are again added and the mixture is allowed to standffor 12 hours out of contact with air. 'A "yield of 90% was obtained. The reaction place according to the following equake tion 3Ha0 NH:

clear solution is then run into 100 cc. concent-rated hydrochloric acid. The arsphenamine is purified by dissolving it in -metha nol whereby it is separated from inorganic materials and subse uently 'preci itated by passing the solution into other. The reaction takes place according to the following equation:

this 22nd day of June, A. D. 1926.

A-RTHUB BINZ. OURT RATH.

ield 90 Process for the preparation of arsenic 

